Combined long and short distance wireless communication system and its method

ABSTRACT

This invention provides a combined long and short distance wireless communication system and method thereof. A dual distance terminal provides subscribers with the long and short distance wireless communication service and guarantees that the service isn&#39;t interrupted when switching between different networks occurs. A remote distance base station provides the dual distance terminal with remote distance wireless access. A short distance AP provides the dual distance terminal with short distance wireless access. A dual distance network server connects the remote distance base station and the short distance AP to switch between networks and make the dual distance terminal access the network to which is switched. The present invention enables the dual distance terminal within the coverage of the long and short distance wireless system to communicate with the long distance networks and automatically switch to short distance wireless local area networks (WLAN) when the dual distance terminal enters the short distance WLAN so that seamless switch is achieved. The subscribers having different priority levels access different short distance WLANs with different levels after authority identification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a wireless communication system and itsmethod, more specially, to a wireless communication system whichcombines long and short distance wireless communication techniques andachieves seamless switch of links. This invention belongs to the fieldof communication techniques.

2. Background of Prior Art

In current mechanisms of communication systems, GSM/GPRS and the future3G (third generation) are all long distance communication (LDC). Themajor characteristics for long distance communication include thecoverage of large area, installation with low cost, and operation withhigh cost and low transmission rate, etc. The long distancecommunication can be referred as to a concept of “ocean”. Recent 802.11and BT, for example, belong to the short distance communication (SDC).The major characteristics of short distance communication include theuse in office areas and certain business areas, the coverage of limitedareas, installation with high cost, operation with low cost and hightransmission rates, etc. The short distance communication can also bereferred as to a concept of “island”. The networks of the short distancecommunication are separated from each other, and have been significantlylimited to a certain area respectively.

In GSM900/1800 networks, and the interacting networks of GSM/GPRS andthe third generation mobile communication, all of them embody theconcept of long distance, i.e. the concept of “ocean”. The operationmodes employed are multiple access modes such as TDMA, CDMA. However, inlong and short distance communication networks, short distancecommunication generally employs operation modes such as CSMA/CA whichare suitably used for short distance transmission. Meanwhile, in longdistance communication networks (LDCN), although the transmission powersthereof are always very large, the transmission powers are limited dueto the limitation of Local Area Networks (LAN) such as WLAN networks, sothat the characteristics of “island” is present. Furthermore, withrespect to long distance communication networks, short distancecommunication networks (SDCN) have the advantages of wide bands, fasttransmission rates, low cost etc.

There exists a need to combine long distance communication networks andshort distance communication networks to complement the advantages foreach other. Thus, a terminal can receive the services from long andshort distance communication networks according to different requests.For example, the terminal may obtain a voice service with long distancecommunication networks whereas obtain a data service with short distancecommunication networks. That is, in long and short distancecommunication networks, the characteristics of that short distancecommunication is present in long distance communication networkcoverage.

SUMMARY OF THE INVENTION

An object of the present invention Is therefore to provide a wirelesscommunication system and method which can combine long and shortdistance communication techniques.

Another object of the present invention is to provide a wirelesscommunication dual distance terminal which can combine long and shortdistance communication techniques.

Yet another object of the present invention is to provide a wirelesscommunication dual distance network server which can combine long andshort distance communication techniques.

The present invention may achieve seamless switch such as automaticswitching, capacity evaluation and security issues and the likes when auser enters an area covered by both long and short distance wirelesscommunication while guarantee the long distance wireless communicationso that the user may use short distance wireless communication andaccess whole networks through the short distance wireless access point(AP), Thus, the two types of network resources can be more effectivelyused.

To achieve above objects of the prevent invention, according to oneaspect of the present invention, a combined long and short distancewireless communication system comprises: a dual distance terminal forproviding subscribers with long and short distance communicationservices, at least one remote distance base station for providing remotedistance wireless access for the dual distance terminal, at least oneshort distance access point (AP) for providing short distance wirelessaccess for the dual distance terminal, and a dual distance networkserver for connecting the remote distance base station through the shortdistance AP to execute network switching for the dual distance terminaland enabling the dual distance terminal to access the network to whichit is switched.

According to another aspect of the present invention, a wirelesscommunication method using combined long and short distance wirelesscommunication systems, comprising steps of scanning a dual distanceterminal to determine whether it is located in a service area covered bya short distance access point upon powering on; entering a shortdistance communication network through the short distance access pointif the dual distance terminal is located within the service area coveredby the short distance access point, and informing a dual distance homeserver of the position of the dual distance terminal; searching for abase station for a long distance communication service if the dualdistance terminal is not located in the area covered by any one of theshort distance access points, entering a long distance communicationnetwork through a long distance access network, and informing the dualdistance home server of the position of the dual distance terminal.

According to yet another aspect of the present invention, a dualdistance network server used for a combined long and short distancewireless communication system, comprising:

-   -   a data service function entity for detecting whether a long and        short distance data transmission occurs, if it occurs, then        providing a connection service for said data transmission;    -   a memory function entity for storing data that may be missed at        the time of memory switching, and sending the stored data to a        terminal via said data service function entity after said        terminal switching is completed, in order to implement seamless        switch for the terminal between a long distance communication        network and a short distance communication network;    -   a dual distance home server for registering the dual distance        character parameters of the dominated dual distance terminals,        obtaining terminal switch information via said data service        function entity when dual distance switch occurs, updating the        terminal data; and informing said data service function entity        of terminal-related dual distance information when a query        regarding the terminal exists;    -   an external network interface unit for connecting dual distance        network and an interface of external networks.

For the dual distance terminal of the invention, it has to adaptconfiguration of both the long distance and short distance communicationnetworks so that the dual distance terminal may move in both networks,the dual distance terminal comprises:

-   -   a short distance communication function entity having a short        distance radio frequency function module for functioning as        physical layer, part of MAC layer or link layer and operating in        a short distance communication network to obtain data        information;    -   a long distance communication function entity having a long        distance radio frequency function module for functioning as        physical layer and part of link layer;    -   a network switch condition judging function entity for        performing network switching for the dual distance terminal        based on the corresponding dual distance switch condition        judging and instructing the short distance communication        function entity or the long distance communication function        entity to send a beacon signal to the dual distance network        server;    -   a common function entity for implementing display and input and        output functions of the terminal.

The combination of long and short distance wireless communicationaccording to the invention brings a lot of convenience, and changes thestatus of separation of the architectures of long distance and shortdistance radically. The present invention has the advantages as follows:

-   -   at any time, a real-time transmission may be achieved by the        long distance wireless communication:    -   when a mobile terminal is allowed to enter the short distance        wireless LAN, it can automatically switching to the short        distance communication mechanism with priority, and the        transmitting traffic stream of the subscriber would not be        interrupted so that seamless switch can be achieved;    -   when the mobile terminal move out the short distance wireless        LAN, It can automatically switch to the long distance        communication network, and the transmitting traffic stream for        the subscriber would not be interrupted so that seamless switch        can be achieved;    -   when the other subscriber terminal in the system according to        the invention is calling and querying any one of the terminal        allowed to be accessed, the system according to the invention        may guarantee the subscriber could be accessed either in the        short distance communication LAN or in the short distance        communication network.

BRIEF DESCRIPTION OF THE DRAWINGS

Above and/or other objects and advantages of the present invention willbecome apparent and more readily appreciated from the followingdescription of the embodiments, taken in conjunction with the accompanydrawings of which:

FIG. 1 is a schematic diagram showing the structure of according to anembodiment of the present invention.

FIG. 2 is a flow chart showing the operation according to the embodimentof the invention.

FIG. 3 is a schematic diagram showing the structure of the dual distancecommunication network server function module of the invention.

FIG. 4 is a flow chart when the dual distance communication networkserver performs switching.

FIG. 5 is a schematic diagram showing the structure of the dual distanceterminal according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention constructs a wireless communication system as astructure of “ocean+island”. According to the wireless communicationsystem of the present invention, remote distance base stations cover allthe effective areas; short distance access points (AP) cover areas suchas offices, residents, and business areas which subscriber density isrelatively high. A long and short distance communication server connectsthe short distance APs with the remote distance base stations. Aplurality of dual distance terminals may freely move within the allareas covered by the short distance APs and the remote distance basestations.

The Operation Principle of the Present Invention

When a dual distance terminal is powered on, first, it detects whetherit is located in the service area covered by a certain short distanceAP. If it is yes, then the dual distance terminal accesses the networkthrough the short distance AP, and informs a dual distance home serverof the position thereof. If the dual distance terminal is not within thearea covered by any one of the short distance APs, then it searches fora base station for a long distance communication service, accessesnetwork through the remote distance base station, and Informs the dualdistance home server of position thereof.

When a dual distance terminal located in the long distance communicationnetwork enters any one of the service areas covered by the shortdistance APs, the dual distance terminal will detent the short distanceAP. If the short distance signal thereof is above a predeterminedthreshold, the dual distance terminal will automatically switch to shortdistance communication frequency band, and begin to access the networkvia the short distance AP. The data transmission carried out by the longdistance communication network is then carried out by the short distancecommunication network to achieve seamless switch. Further, the terminalinforms its home server of the area which it locates now. The server Isin charge of the query and communication to the terminal from otherterminals in the network.

When a dual distance terminal located in the short distancecommunication networks moves out of the service area covered by theshort distance communication networks and enters the long distancenetwork, the terminal detects the short distance AP signal. If the shortdistance signal thereof is below a predetermined threshold, the dualdistance terminal automatically switches to the long distance network.The data transmission carried out by the short distance is then carriedout by the long distance network to achieve seamless switch. Then, theterminal informs its home server that it has already located in the areacovered by the long distance network. After that, the server is incharge of the query and communication to the terminal from otherterminals in the network.

When a dual distance terminal located in the long distance networksrequests to enter any one of the service areas of the short distanceAPs, if the AP in the area in which the terminal locate rejects theaccess of dual distance terminal due to security or other issues, thedual distance terminal then still keeps the long distance communication.

When a dual distance terminal moves from one short distance cell toanother short distance cell, the dual distance terminal identify thearea, into which the dual distance terminal will enter, covered by theshort distance AP. Then the dual distance terminal transmits informationof the corresponding cell to the dual distance communication networkserver so as to achieve the switching between the short distance cells.After that, the dual distance terminal informs the home server among thedual distance network communication servers that it has already beenenter into the area covered by another short distance communicationnetwork. The home server is then in charge of the queries andcommunications to the dual distance terminal from the other terminals inthe networks.

The invention will be described by using a combined dual distancewireless communication system which is formed by combining a longdistance GSM/GPRS with a short distance WLAN by way of example. Thenetwork architecture of the wireless communication system according tothe invention comprises GSM/GPRS base stations, a long distance accessrelated network function entity, wireless LAN APs, a short distanceaccess related network function entity, a dual distance communicationnetwork server for linking the long distance GSM/GPRS networks and theshort distance wireless LANs, dual distance terminals compatible withlong distance communication network and short distance communicationnetwork. FIG. 1 shows the basic network structure of the invention.However, it should be noted that the present invention is not limited tothe example shown as FIG. 1, it may include a combined architectureformed by combining a long distance 3G communication with a shortdistance WLAN or a combined architecture of other long distance andshort distance communication modes.

Now referring to FIGS. 1 and 2, the operation of a dual distancecommunication network formed by combining GSM/GPRS with WLAN accordingto an embodiment of the invention will be described in more detail.

1. In the Dual Distance Network, After the Dual Terminal Powered On.

For the system described in the invention, the dual terminalautomatically searches for the network environment currently locatedafter it is powered on by the subscriber. If the dual distance terminaldetects that a wireless local area network WLAN network exists and doesnot require authority identification at present, the dual distanceterminal then accesses the WLAN network directly. On the contrary, ifthe result of the detection indicates that current WLAN network requiresauthority identification, the dual distance terminal then performsaccess authority identification via WLAN. If the authorityidentification is successful, the dual distance terminal accessescurrent WLAN network. Otherwise, the dual distance terminal willcontinue the detection and enter into the long distance GPRScommunication network.

After the dual distance terminal enters into the WLAN network, the dualdistance terminal may perform data transmission by accessing the dualdistance communication server via the short distance WLAN network.

2. Switching Between Networks

2.1 Switching From the Short Distance WLAN Communication Networks to theLong Distance GPRS Communication Networks

When the dual distance terminal moves out of the short distance WLANnetwork and enter into the GPRS network, the dual distance terminal maymake judgment by using a predetermined switching condition. If apredetermined threshold for switching (which may refer to a non-usablethreshold of a short distance communication network signal or may referto a non-optimal threshold of a short distance communication networksignal) is satisfied, the dual distance terminal terminates datatransmitted through the WLAN radio frequency function entity (not shown)with the predetermined switching condition, and activates the longdistance communication function entity and uses it to implement thepossible sequent data transmission. If the service level of this dualdistance terminal requires a seamless switching, then the dual distanceterminal terminates the data being transmitted by the WLAN radiofrequency function entity. At the same time, it sends beacon signal forswitching between the shot distance communication network and the longdistance communication network to the short distance AP, from which thecommunication is switched, by the short distance communication functionentity in the terminal. The beacon signal is transmitted to the dualdistance communication network server by the short distance AP. Afterreceiving the corresponding beacon signal, the dual distance networkserver informs the long distance communication function entity to beaccessed by the dual distance terminal of the receipt, and determinesthe service queue position which the dual distance terminal is arrangedin the long distance network function entity (provided in the dualdistance network server, not shown) based on its service level.

Meanwhile, the dual distance communication network server stores thedata packets which may be missed in the switching process to protect thedata packets, the stored data packets are forwarded to the dual distanceterminal after the switching is completed, thereby preventing data forthe dual distance terminal from lost during the switching.

2.2 Switching From the Long Distance GPRS Networks to the Short DistanceWLAN Networks

When the dual distance terminal moves out of the long distance GPRSnetwork and enters into the short distance WLAN network, the dualdistance terminal may make judgment by using switching condition. If thepredetermined threshold for switching is satisfied, the dual distanceterminal terminates the data transmitted through the long distancecommunication function entity with the predetermined switchingcondition, and activates the short distance communication functionentity and uses it to implement the possible sequent data transmissions.

When terminating the data being transmitted by the long distancecommunication function entity, the dual distance terminal further sendsone beacon signal of long and short distance switching to the GPRSservice function entity, from which switch is performed, by the basestation and the corresponding GPRS network function entity in the dualdistance terminal. The beacon signal is transmitted to the dual distancenetwork server by the GPRS function entity. After receiving thecorresponding beacon signal, the dual distance network server informsthe short distance communication function entity of the receipt, anddetermines the priority of the dual distance terminal in the shortdistance communication network function entity based on its servicelevel.

Meanwhile, the dual distance communication network server stores thedata packets which may be missed in the switching process to protect thedata packets, the stored data packets are forwarded to the dual distanceterminal after the switching is completed, thereby preventing data forthe dual distance terminal from lost during the switching.

2.3 Switching From One Short Distance Communication Network to AnotherShort Distance Communication Network

When the dual distance terminal moves from one short distance cell toanother short distance cell, the dual distance terminal identifies theshort distance AP to which it will enter, and sends the cell informationto the dual distance network server, thereby implementing the switchingbetween the short distance cells. The dual distance terminal theninforms the home server among the dual distance network servers that ithas already entered in the area covered by another short distancecommunication network, and the home server is in charge of the query andcommunication to it from the other terminals in the network.

2.4 Automatic Switching

The subscriber may define the priority level of the switching in advanceif necessary so that the dual distance terminal may perform automaticswitching. The priority level is set according to charging fee,transmission rates, quality stability and the likes, for example. Thedual distance terminal automatically identifies the switching accordingto the priority level. Further, when the subscriber is located withinthe areas covered by short distance AP, it may not select the use ofshort distance AP, but may directly select the use of long distancecommunication.

3. Scanning and Detecting

With respect to the long and short distance communication networkarchitecture, the most important problems are as follows:

-   -   (1) the dual distance terminal keeps the long distance and the        short distance radio frequency entity in operating state all the        time, and detects the possible long distance or short distance        communication network environment in real-time, continuously        feeds the detected results back to the dual distance terminal        switching management mechanism, the detected results are        reported to the dual distance network server through the        existing network periodically or as desired;    -   (2) the dual distance termnal keeps the radio frequency function        entity in the network in which it locates in operating state all        the time, and activates the corresponding radio frequency        function entities for the other networks periodically or        non-periodically to detect the candidate networks;    -   (3) The dual distance terminal may keeps the radio frequency        function entity in the network in which it locates in operating        state all the time, and does not scan and detect the other        networks. In this case, the dual distance terminal detects the        other networks only when the existing network is not available;

The detection for candidate networks with non-periodically activatingthe corresponding radio frequency function entity may be carried out bymeans of some specific algorithms, such as a viable-step detectionmethod which the time interval of finally finding the occurrence ofother networks is used as a function.

4. Switching Conditions

The switching conditions can be selected according to differentsituations for the network user, hereafter is the two examples of theswitching conditions. It should be noted that the present invention didnot limit the two switching conditions as described below, otherconditions can also be used in the present invention.

-   -   (1) The network switching Is performed based on priority level.        That is, as long as the dual distance terminal finds the        occurrence of the network with higher priority level, then it        switches to the network with higher priority level, no matter        whether the network which is used currently is available or not.        The subscribers can define the priority levels of various        wireless networks as desired, for example, transmission rate,        usage fee and the likes.    -   (2) The dual distance terminal switches to other networks only        when the currently used wireless network signals may not be        received. This switching condition means that the switch is        performed only when the wireless network in which the dual        distance terminal currently locates is not available. In        contrary, the switch is not performed if the network in which        the dual distance locates is available, even though there is a        network with a higher priority level.

FIG. 3 is a schematic diagram showing the dual distance network server.The dual distance network server comprises a data service functionentity, a memory function entity, a dual distance home server, and anexternal network interface. The data service function entity detectswhether a long or short distance data transmission occurs. The datatransmission includes data transmission between the dual distanceterminal located in a long distance communication network and the dualdistance terminal located in a short distance communication network, andthe data transmission between the dual distance terminal located In along or a short distance communication network and external networks.The data transmission between the dual distance terminals located in along (or short) distance communication network can be carried out by thelong (or short) distance network function entity (provided in the dualdistance network server, not shown). When a long and a short distancedata transmission occurs, a connection service is provided to the datatransmission.

A beacon signal of the dual distance terminal forwarded by the long(short) distance network function entity is detected to determinewhether the dual distance terminal performs a switching between the longand short distance communication networks. If so, then a new terminalinformation (for example, a network name to which the terminal isswitched) is informed to a dual distance home register.

The memory function entity stores the data which is possibly missed atthe time of switching. Further, the memory function entity forwards thestored data to the terminal via the data service function entity afterthe switching is completed so that the terminal can achieve a seamlessswitching between the long distance communication network and the shortdistance communication network.

The dual distance home server records the dual distance characteristicparameters of the managed dual distance terminals, such as thesituations of the located network, priority level parameters of theterminals and the likes. The terminal switching information Can beobtained via the data service function entity when a switching occursbetween the long distance communication network and the short distancecommunication network. The terminal data Is updated. Theterminal-related dual distance information is Informed to the dataservice function entity when a query regarding the terminal occurs.

The external network inter-face connects the long distance communicationnetwork and short distance communication network to the externalnetwork. The external network interface comprises a wireless interface,an interface for wire network, and an interface for other wirelessnetworks.

FIG. 4 is a flow chart showing the operation process when the dualnetwork server performs switching. When the dual distance terminal movesfrom one network to another network, the dual distance network servercooperates with the dual distance terminal for performing switch. Theprocess of the switching Is as follows:

-   -   first step: detecting the dual distance beacon signal of the        dual distance terminal by the long (or short) distance network        function entity, checking whether a switching occurs, if it is        not, then the detection is repeated; if it is yes, the flow        turns to next step;    -   second step: updating the subscriber information registered in        the dual distance home register;    -   third step: determining whether or not data transmission occurs,        if it is not, the flow returns to the first step;    -   fourth step: determining whether or not there exist a need for        seamless switching, if it is not, the flow returns to the fist        step;    -   fifth step: buffering the transmitted data, and forwarding the        buffered data to the dual distance terminal after the switch is        completed.

FIG. 5 is a schematic diagram showing the functional structure of thedual distance terminals according to an embodiment of the invention. Thedual distance terminal according to the present invention can operatewithin the long distance communication network and the short distancecommunication network during it moves in both networks. Therefore, it isnecessary for the dual distance terminals of the invention to have astructure adaptive to the features of both networks. The dual distanceterminal comprises at least a short distance communication functionentity, a long distance communication function entity, a dual networkswitch condition judging function entity, and a common function entity.

The short distance communication function entity includes a shortdistance radio frequency function module and may achieve the functionsof the physical layer and a part of a MAC layer or link layer. The shortdistance communication function entity operates in the short distancecommunication network and obtains data information.

The long distance communication function entity Includes a long distanceradio frequency function module and may achieve the functions thephysical layer and a part of link layer.

The network switch condition judging function entity performs networkswitching for the dual distance terminal based on the corresponding dualdistance switch condition judging and instructs the short distancecommunication function entity or the long distance communicationfunction entity to send a beacon signal to the dual distance networkserver;

The common function entity includes basic functions such as display,input and output contained in conventional terminals;

The dual distance terminal controls the operating modes of the radiofrequency function module in the long (short) communication functionentity by using the dual network switch condition judging functionentity. The operating modes of the radio frequency function modulescomprise (1) the long radio frequency function module and short radiofrequency function module operate simultaneously; (2) performs theviable-step operating mode according to circumstances; and (3) only whenone network does not exist, the radio frequency function entitycorresponding to the other network is activated so as to search for theother network.

In the present invention, alternatively, the dual distance terminal mayalso comprise a data management and buffering function entity whichmanages and buffers the corresponding data during the switching.

Unlike the conventional terminals, the dual distance terminal of theinvention has both the long distance and the short distancecommunication function entity. Therefore, it can detect or automaticallysearch the possible short distance communication networks such as WLANand the long distance communication networks such as GSM/GPRS or 3Gsimultaneously. Further, it can also perform the short distance or longdistance data transmission services (including voice which is a specificdata service) by means of the short distance and the long distancefunction entities. Another difference from the conventional terminals isin that the dual distance terminal of the invention also comprises anetwork switch condition judging function entity. The network switchcondition judging function entity performs network switching for thedual distance terminal based on the corresponding dual distance switchcondition judging and instructs the short distance communicationfunction entity or the long distance communication function entity tosend a beacon signal to the dual distance network server. Further, itmay optionally comprise a data management and buffering function entitywhich manages and buffers the corresponding data during the switching.Thus, the data transmission requested by the common function entity doesnot be interrupted due to the switching.

Although the present Invention has been described by way of exemplaryembodiments, it should be understood that many changes and substitutionsmay further be made by those skilled In the art without departing fromthe scope of the present invention which is defined by the appendedclaims.

1. A combined long and short distance wireless communication systemcomprising: a dual distance terminal for providing subscribers with longand short distance communication services; at least one remote distancebase station for providing remote distance wireless access for said dualdistance terminal; at least one short distance access point (AP) forproviding short distance wireless access for said dual distanceterminal; and a dual distance network server for connecting said atleast one remote distance base station and said at least one shortdistance AP to execute network switching for said dual distance terminaland enabling said dual distance terminal to access the network to whichit is switched, storing data that may be missed during switching andsending the stored data to said dual distance terminal after saidterminal switching is completed. 2-3. (Canceled)
 4. A dual distanceserver used for a combined long and short distance wirelesscommunication system as claimed in claim 1, comprising: a data servicefunction entity for detecting whether or not the occurrence of a longand short distance data transmission is, if it is, then providing aconnection service for said data transmission; a memory function entityfor storing data that may be missed during switching, and sending thestored data to a dual distance terminal via said data service functionentity after said network switching is completed; a dual distance homeserver for registering the dual distance communication parameters of thedominated dual distance terminals, obtaining network switch informationvia said data service function entity in the case where dual distanceswitch occurs, updating data of the dual distance terminal, andinforming said data service function entity of dual distance terminalinformation when a query regarding the terminal exists; and an externalnetwork interface unit for connecting dual distance network and aninterface of an external network.
 5. The dual distance server accordingto claim 4, wherein said external network interface comprises a wirelessinterface, an interface for wire network, and an interface for otherwireless networks.
 6. A dual distance terminal used for a combined longand short distance wireless communication system as claimed in claim 1,comprising: a short distance communication function entity having ashort distance radio frequency function module for functioning asphysical layer, part of MAC layer or link layer and operating in a shortdistance communication network to obtain data information; a longdistance communication function entity having a long distance radiofrequency function module for functioning as physical layer and part oflink layer; a network switch condition judging function entity forperforming network switching for the dual distance terminal based on thedual distance switch condition and instructing the short distancecommunication function entity or the long distance communicationfunction entity to send a beacon signal to the dual distance networkserver; a data management and buffering function entity for storing datathat may be missed during switching and sending the stored data to acommon function entity in the high level of the dual distance terminalafter said network switching is completed; and a common function entityfor implementing display, input and output functions of the terminal. 7.(Canceled)
 8. A wireless communication method using combined long andshort distance wireless communication systems, comprising steps:detecting a dual distance terminal to determine whether it is located ina service area covered by a short distance access point; entering ashort distance communication network through the short distance accesspoint in the case where the dual distance terminal is located within theservice area covered by the short distance access point, and informing adual distance home server of the position of the dual distance terminal;searching for a base station for a long distance communication serviceif the dual distance terminal is not located in the area covered by anyone of the short distance access points, entering a long distancecommunication network through a base station for a long distancecommunication service, and informing the dual distance home server ofthe position of the dual distance terminal; switching between a longdistance communication network and a short distance communicationnetwork when the dual distance terminal enters the short distancenetwork service area from the long distance network service area, orenters the long distance network service area from the short distancenetwork service area, and storing data that may be missed duringswitching, and sending the stored data to a dual distance terminal viasaid data service function entity after said network switching iscompleted.
 9. The wireless communication method according to claim 8,further comprising the step of when the dual distance terminal detectsthat a wireless local area network (WLAN) exists in the short distancenetwork, the dual distance terminal then accesses the WLAN network; thedual distance terminal continues the detection and enters into the longdistance network in the case where the entrance into the WALN network isunsuccessful.
 10. The wireless communication method according to claim9, further comprising the step of the dual distance terminal performsdata transmission by accessing the dual distance server via the shortdistance WLAN network in the case where the dual distance terminalenters into the short distance WLAN network.
 11. The wirelesscommunication method according to claim 9, further comprising the stepof the dual distance terminal terminates data transmission through ashort distance radio frequency function entity and activates a longdistance communication function entity and performs the sequent datatransmission if a predetermined threshold for the switching is satisfiedduring the dual distance terminal moves out of the short distance WLANnetwork and enters into the long distance network so that network switchis completed.
 12. The wireless communication method according to claim11, wherein the predetermined threshold for the switching is anon-usable threshold of a short distance network signal or a non-optimalthreshold of a short distance network signal.
 13. The wirelesscommunication method according to claim 11, further comprises the stepsof in the case where the dual distance terminal requests seamlessswitching from the short distance network to the long distance networkbased on its service level, the dual distance terminal terminates datatransmission through the short distance radio frequency function entitythe dual distance terminal and sends a beacon signal to the shortdistance AP from which is switched through the short distancecommunication function entity in the terminal, the beacon signal is thentransmitted to the dual distance network server by the short distanceAP, the dual distance network server informs the long distancecommunication function entity to be accessed by the dual distanceterminal of the receipt, and determines the service queue position whichthe dual distance terminal is arranged in the long distance networkfunction entity based on its service level.
 14. (Canceled)
 15. Thewireless communication method according to claim 8, further comprise thestep of the dual distance terminal terminates data transmission througha long distance radio frequency function entity and activates a shortdistance communication function entity and performs the sequent datatransmission if a predetermined threshold for the switching is satisfiedduring the dual distance terminal moves out of the long distance WLANnetwork and enters into the short distance network so that networkswitch is completed.
 16. The wireless communication method according toclaim 15, further comprises the steps of in the case where the dualdistance terminal requests seamless switching from the long distancenetwork to the short distance WLAN network based on its service level,the dual distance terminal terminates data transmission through the longdistance radio frequency function entity and sends a beacon signal tothe long distance network function entity from which is switched throughthe long distance communication function entity in the terminal, thebeacon signal is then transmitted to the dual distance network server bythe lone distance communication function entity, the dual distancenetwork server informs the short distance communication function entityto be accessed by the dual distance terminal of the receipt, anddetermines the service queue position which the dual distance terminalis arranged in the short distance network function entity based on itsservice level.
 17. (Canceled)
 18. The wireless communication methodaccording to claim 9, further comprises the step of when the dualdistance terminal moves from one short distance cell to another shortdistance cell, the dual distance terminal identifies the short distanceaccess point to which it enters, and sends the cell information to thedual distance network server to perform the switching between the shortdistance cells.
 19. The wireless communication method according to claim18, further comprises when the dual distance terminal moves from oneshort distance cell to another short distance cell, the dual distanceterminal informs the home server among the dual distance network serversthat it has already entered in said another short distance cell, and thehome server manages the query and communication to it from the otherterminals in the network.
 20. (Canceled)
 21. The wireless communicationmethod according to claim 31, wherein the detection for candidatenetworks with non-periodically activating the corresponding radiofrequency function entity is carried out by using a viable-stepdetection method which the time interval of finally finding theoccurrence of other networks is used as a function. 22-26. (Canceled)27. The wireless communication method according to claim 8, wherein theprocess of the dual distance server cooperating with the dual distanceterminal to perform the switch comprises: first step: detecting the dualdistance beacon signal of the dual distance terminal by the long (orshort) distance network function entity to determine whether or not aswitching occurs; second step: updating the subscriber informationregistered in the dual distance home register; third step: determiningwhether or not data transmission occurs, if it is not, the flow processreturns to the first step; fourth step: determining whether or not thereexists a need for seamless switching, if it is not, the process returnsto the fist step; fifth step: buffering the transmitted data, andforwarding the buffered data to the dual distance terminal after theswitch is completed.
 28. The wireless communication method according toclaim 15, wherein when the dual distance terminal located in the longdistance network requests to enter any one of the service areas coveredby the short distance access points, and the dual distance terminal cannot access the short distance network, then the dual distance terminalstill operates the long distance communication.
 29. The wirelesscommunication method according to claim 8, wherein the subscriberdefines the priority levels of the switching in advance as desired sothat the dual distance terminal performs automatic switching.
 30. Thewireless communication method according to claim 8, wherein said step ofdetecting a dual distance terminal to determine whether it is located ina service area covered by a short distance access point furthercomprises: the dual distance terminal keeps the long distance and theshort distance radio frequency entity in operating state, and detectsthe long distance or short distance communication network environment inreal-time, feeds the detected results back to the dual distance terminalswitching management mechanism, reports the detected results to the dualdistance network server through the existing network periodically or asdesired.
 31. The wireless communication method according to claim 8,wherein said step of detecting a dual distance terminal to determinewhether it is located in a service area covered by a short distanceaccess point further comprises: the dual distance terminal keeps theradio frequency function entity corresponding to the network in which itlocates in operating state, and activates the radio frequency functionentities for the other networks periodically or non-periodically todetect the candidate networks.
 32. The wireless communication methodaccording to claim 8, wherein said step of detecting a dual distanceterminal to determine whether it is located in a service area covered bya short distance access point further comprises: the dual distanceterminal keeps the radio frequency function entity corresponding to thenetwork in which it locates in operating state, and does not detect theother networks until the existing network is not available.
 33. Thewireless communication method according to claim 8, wherein saidpredetermined conditions for the switching refers to switch the dualdistance terminal to a network with higher priority level in the casewhere the network with higher priority level exists.
 34. The wirelesscommunication method according to claim 8, wherein said predeterminedconditions for the switching refers to switch dual distance terminal toother networks only when the currently used wireless network signals cannot be received.
 35. The wireless communication method according toclaim 11, wherein said predetermined conditions for the switching refersto switch the dual distance terminal to a network with higher prioritylevel in the case where the network with higher priority level exists.36. The wireless communication method according to claim 11, whereinsaid predetermined conditions for the switching refers to switch dualdistance terminal to other networks only when the currently usedwireless network signals can not be received.
 37. The wirelesscommunication method according to claim 13, wherein said predeterminedconditions for the switching refers to switch the dual distance terminalto a network with higher priority level in the case where the networkwith higher priority level exists.
 38. The wireless communication methodaccording to claim 13, wherein said predetermined conditions for theswitching refers to switch dual distance terminal to other networks onlywhen the currently used wireless network signals can not be received.